1. Field of the Invention
The present invention relates to polymer-bonded polycyclic aromatic hydrocarbons and in particular, polymer-bonded perylene, terrylene and quaterrylene compounds having a nitrogen-containing heterocycloaliphatic substituent and to compositions such as, e.g., printing inks which comprise these polymer-bonded polycyclic aromatic hydrocarbons as colorants.
2. Discussion of Background Information
Counterfeiting and market diversion of mass produced goods are facilitated if the products are handled on a lot base rather than on an individual item base. In such case counterfeit or diverted products are easily introduced into the supply chain. Producers and retailers would like to be in a position to distinguish their original products from such counterfeit or diverted (parallel imported or smuggled) products at the level of the individual unit that is sold.
Further, secure documents such as currency, passports, or identity cards are increasingly counterfeit around the world. This situation is a very critical issue for governments and society in general. For example criminal organizations may use fake passports or identity cards for human beings traffic. As reprographic technologies become more and more sophisticated, it becomes even more difficult to make a clear distinction between a fake document and the original. Document security has therefore a considerable impact on the economy of the countries and also on the victims of illicit traffic involving counterfeit documents.
In an attempt to prevent counterfeiting marking is currently used extensively for the recognition, identification and authentication of individual items. The marking may be applied, for example, in the form of indicia such as 1-dimensional barcodes, stacked 1-dimensional barcodes, 2-dimensional barcodes, 3-dimensional barcodes, a data matrix. and the like. The application of markings is frequently carried out by a printing process which uses a printing ink with specific optical properties that are imparted to the ink by one or more substances contained therein such as, e.g., luminescent dyes, pigments, or cholesteric liquid crystal compounds.
A class of compounds which is suitable for use in, e.g., printing inks for marking purposes are compounds having a perylene, terrylene or quaterrylene skeleton. Perylene, terrylene and quaterrylene display fluorescence and there are many derivatives of these compounds which are known and may theoretically be employed as pigments in compositions for marking such as printing inks and the like. However, a drawback of these compounds is their often unsatisfactorily low solubility or dispersibility in liquid media such as those which are useful in printing inks. This low solubility/dispersibility limits the suitability of these compounds as colorants for liquid compositions in general. It would thus, be advantageous to be able to increase the solubility and/or dispersibility of perylene, terrylene and quaterrylene dyes in liquid media and in particular, liquid media for use in printing inks.